Positioning system for removable data storage cartridges

ABSTRACT

A system for positioning a data storage cartridge in a read/write mechanism in which alignment holes in the cartridge are pre-aligned to alignment pins on the read/write mechanism. The system includes a beveled recess in the front surface of the cartridge, a pair of holes in the bottom surface of the cartridge and four alignment pins affixed to the read/write mechanism. The third and fourth alignment pins are oriented perpendicular to and project out toward the second planar surface of the cartridge. The first, second, third and fourth alignment pins are disposed such that when the cartridge reaches the pre-aligned position the first alignment pin bottoms out in the beveled recess, the second alignment pin abuts the first planar surface at a location away from the beveled recess, the third alignment pin is substantially aligned with one of the holes in the second planar surface and the fourth alignment pin is substantially aligned with the other of the holes in the second planar surface.

FIELD OF THE INVENTION

The invention relates generally to data storage devices that useremovable cartridges and, more particularly, to a system for properlypositioning a removable data storage cartridge in a read/writemechanism.

BACKGROUND OF THE INVENTION

A widely used medium for storing data is recording tape, which istypically a polymer tape with a magnetic coating. Tape cartridges areone of the most popular formats for storing data on tape. Tapecartridges are usually smaller and less expensive than reel-to-reeltapes. Two widely used types of tape cartridges are the dual reelcartridge and the single supply reel cartridge. By enclosing the tapewithin a cartridge, the tape and the data stored on the tape are betterprotected from damage than the more exposed reel-to-reel tapes. In adual reel tape cartridge, both the supply reel and the take-up reel arehoused in the cartridge. In a single supply reel tape cartridge, thetake-up reel is built into the tape drive along with an automatic tapethreading mechanism.

In many tape cartridge drive systems, the tape cartridges are carriedinto the proper position in the tape drive on a tray that moves in andout of the tape drive. The tray moves back and forth between anextended/loading position for receiving a tape cartridge and aretracted/operating position in the drive for positioning the cartridgefor read and write operations. A paired hole/slot positioning system iscommonly used to accurately position the cartridge in the tape drive asthe cartridge is loaded. In this system, a hole and a slot are formed inthe bottom of the cartridge along a line parallel to the vertical planeof the front of the cartridge. As the tray moves to the retractedposition, it carries the cartridge in and down over a pair of alignmentpins affixed to the tape drive. One of the alignment pins projects intothe hole in the bottom of the cartridge. The other alignment pinprojects into the slot. The hole/slot pair on the cartridge and thealignment pins on the tape drive are located such that when the pinsproject into the hole and slot, the cartridge and corresponding the tapewithin the cartridge, will be properly positioned in the tape drive.

In order to accommodate some initial misalignment between the hole andslot and the alignment pins, the edges of the hole and slot arechamfered or the ends of the pins are chamfered, or both. In this way,if the cartridge is not precisely aligned as it drops down over thepins, the beveled edges of the chamfers will move the cartridge into theproper position to receive the alignment pins. The size of the hole/slotand pins and their chamfered edges determines how much misalignment canbe accommodated and how much vertical travel is required to get the pinsinto the hole and slot. Making the hole, slot and pins and theirchamfers larger, and increasing the vertical travel, increases theallowable misalignment. It is desirable, however, to minimize oreliminate the vertical travel necessary to properly position thecartridge in the tape drive and to keep the hole, slot and pins and thechamfers as small as possible because all of these factors add cost andcomplexity to the tape cartridge and the tape drive.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a system forpositioning a data storage cartridge in a read/write mechanism in whichalignment holes in the cartridge are pre-aligned to alignment structureson the read/write mechanism. The cartridge may be characterized by afirst planar surface that fronts the tape drive and a second planarsurface perpendicular to and extending away from the first planarsurface. The cartridge is movable in a first direction from a loadingposition to a pre-aligned position in which the cartridge is partiallyinstalled in the read/write mechanism and then in a second directiontransverse to the first direction from the pre-aligned position to analigned operating position in which the cartridge is fully installed inthe read/write mechanism.

The invented system includes a beveled recess in the first planarsurface of the cartridge, a pair of holes in the second planar surfaceof the cartridge and four alignment structures affixed to the read/writemechanism (first, second, third and fourth alignment structures). Thethird and fourth alignment structures, typically pins, are orientedperpendicular to and project out toward the second planar surface of thecartridge. The first alignment structure is disposed in the read/writemechanism such that as the cartridge is moved toward the pre-alignedposition the first alignment structure abuts the beveled recess. Thefirst, second, third and fourth alignment structures are disposed suchthat when the cartridge reaches the pre-aligned position the firstalignment structure bottoms out in the beveled recess, the secondalignment structure abuts the first planar surface at a location awayfrom the beveled recess, the third alignment structure is substantiallyaligned with one of the holes in the second planar surface and thefourth alignment structure is substantially aligned with the other ofthe holes in the second planar surface. One or both of the alignmentholes on the cartridge and the alignment pins on the read/writemechanism may be chamfered to accommodate any misalignment between theholes and the pins.

The invention may also be embodied in a housing for the cartridge. Inthis embodiment, the cartridge housing includes a top, a bottom, and afront and sides connecting the top and bottom. A beveled recess isformed in the front of the housing and a flat surface is located on thefront of the housing at a position away from the beveled recess. A pairof alignment holes are positioned in the bottom of the housing,preferably along a line parallel to the flat surface on the front of thehousing. The beveled recess, flat surface and alignment holes are usedin conjunction with alignment structures in the read/write mechanism, asdescribed above for the system embodiment of the invention, to properlyalign the cartridge when it is installed in the read/write mechanism.

The pre-alignment features of the invention reduce the vertical travelnecessary to properly position the data storage cartridge (a tapecartridge, for example) in the read/write mechanism (a tape drive, forexample) and to keep the alignment holes on the cartridge and thealignment pins on the read/write mechanism and the chamfers as small aspossible.

The various embodiments of the invention may be better understood withreference to the Drawings and the following Detailed Description.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective top side view of a single supply reel tapecartridge constructed according to one embodiment of the invention.

FIG. 2 is a perspective bottom side view of the single supply reel tapecartridge of FIG. 1.

FIG. 3 is a plan view of the bottom of the cartridge of FIG. 1.

FIGS. 4, 5 and 6 are top down plan views of a tape drive constructedaccording to a second embodiment of the invention showing in sequencethe installation of a tape cartridge.

FIG. 7 is a cross section view taken along the line 7—7 in FIG. 5.

FIG. 8 is a cross section view taken along the line 8—8 in FIG. 6.

FIGS. 9-12 show in sequence the installation of a tape cartridge intothe tape drive of FIG. 4 from a perspective view.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described with reference to the tape cartridge 10shown in FIGS. 1-3 and the tape drive 50 shown in FIGS. 4-12. Thedescription of pertinent structural features of each device is followedby a description of the cooperative interaction and operation of the twodevices. Generally, the invented tape cartridge 10 includes a beveledrecess formed in a flat front face of the cartridge for coarsepositioning along with a more precise positioning hole/slot pair in thebottom of the cartridge. These features are used in conjunction withalignment pins or other suitable alignment structures in the tape driveto properly position cartridge 10 in tape drive 50 for read and writeoperations.

Referring first to FIGS. 1-3, a single reel tape cartridge 10 includes ahousing 12, a tape supply reel 14 and tape 16. Reel 14 and tape 16 areshown in the cut-away portion of FIG. 1. Reel 14 includes a hub 15 andflanges 17 extending out from hub. Housing 12 is a generally rectangularbox-like structure configured to enclose a single reel of tape. Housing12 includes a top 18, a bottom 20 and sidewalls 22 extending between thetop and bottom. Tape 16 is accessible to a tape drive through accesswindow 24 on left side 26 of housing 12. A door 28 covers access window24 when cartridge 10 is not installed in a tape drive. Door 28 is pushedopen and held open when cartridge 10 is installed in the tape drive.

Cartridge 10 is installed in the tape drive front side 30 first asindicated by arrow 32 in FIG. 1. Housing bottom 20 and front side 30each include planar surfaces 20 a and 30 a respectively. Planar surfaces20 a and 30 a are perpendicular to one another.

A circular gear 34 is exposed through opening 36 in the bottom 20 ofhousing 12. Gear 34, which is coupled to reel 14, provides the operativeinterface between the tape drive and cartridge 10. Gear 34 is engaged bya mating coaxial gear in the drive mechanism of the tape drive to rotatereel 14.

A beveled recess 38 is formed in a part of front planar surface 30 a ofhousing 12. A pair of alignment holes 40 and 42 are formed in bottomplanar surface 20 a of housing 12. It is desirable, although notnecessary, that holes 40 and 42 be spaced apart as far as practicableacross bottom 20 as measured along a line parallel to front planarsurface 30 a or along a line parallel to a centerline 44. Typically,holes 40 and 42 will be located along a line parallel to front planarsurface 30 a near front side 30 or along a line parallel to a centerline44 near side 26.

Planar surfaces 20 a and 30 a are called out specifically to distinguishother structural features that may be included in bottom 20 and side 30of housing 12. Planar surfaces 20 a and 30 a may be very small coveringonly a minute part of the bottom 20 or side 30 of housing 12, or theymay be much larger covering most of the bottom 20 or side 30 of housing12. For example, planar surface 30 a need only present sufficientsurface area to abut the corresponding alignment structure on tape drive50 as described below. Planar surface 20 a may be two non-contiguousareas localized at alignment holes 40 and 42. In any case, whencartridge 10 is correctly positioned in the tape drive, planar surface20 a is parallel to a first reference plane, designated the A datum, andplanar surface 30 a is parallel to a second reference plane, designatedthe B datum. The A and B datum planes are each perpendicular to a thirdreference plane, designated the C datum.

Referring now to FIGS. 4-12, tape drive 50 illustrates generally theconfiguration of a tape drive typical of those used with single spooltape cartridges, except that tape drive 50 has been adapted for use withthe present invention. Tape drive 50 includes tape guides 52 and 54, amagnetic read/write head 56, a take up spool 58 and a cartridge holder60. When tape cartridge 10 is inserted into tape drive 10 for read andwrite operations, the tape (not shown) passes around first tape guide52, over magnetic read/write head 56, around second tape guide 54 totake up spool 58. Head 56 is mounted to a carriage and actuator assembly62 that positions head 56 over the desired track or tracks on the tape.

The invention utilizes four alignment structures 64, 66, 68 and 70 intape drive 50. Each of these alignment structures is affixed to thehousing, chassis or other stationary part of the tape drive. First andsecond alignment structures 64 and 66 and third and fourth alignmentstructures 68 and 70 are positioned on opposite sides of the front toback centerline 44 of cartridge housing 12 as determined when cartridge10 in installed in tape drive 50. In addition, third and fourthalignment structures 68 and 70 are positioned along a line parallel tothe B datum. This configuration of third and fourth alignment structures68 and 70 in tape drive 50 and alignment holes 40 and 42 ensures thatfront planar surface 30 a is parallel to the B datum when alignmentholes 40 and 42 in cartridge 10 drop down over third and fourthalignment structures 68 and 70.

First alignment structure 64 will abut recess 38 in cartridge 10 to helpalign cartridge 10 to the B and C datums and to position holes 40 and 42over pins 68 and 70 along the B datum (from side to side). Firstalignment structure 64, therefore, must be stationary in a planeparallel to the A datum. First alignment structure 64 may be avertically projecting pin as depicted in the Figures, a horizontallyprojecting bar, or any other structure suitably configured to projectinto and abut recess 38 in cartridge 10.

Second alignment structure 66 will abut front planar surface 30 a ofcartridge 10 to help align cartridge 10 to the B and C datums. However,because second alignment structure 66 does not locate the cartridge fromside to side (first alignment structure 64 does this as it projects intoand abuts recess 38), second alignment structure 66 need only bestationary from front to back. That is to say, second alignmentstructure 66 can move up and down and side to side within the confinesof front planar surface 30 a, but it can't move front to back. Secondalignment structure 66 may be a vertically projecting pin as depicted inthe Figures, a horizontally projecting bar, or any other structuresuitably configured to abut front planar surface 30 a of cartridge 10.

Third and fourth alignment structure 68 and 70 will project into holes40 and 42 in bottom planar surface 20 a of cartridge 10 to preciselyalign cartridge 10 to the B and C datums. Third and fourth alignmentstructures 68 and 70, therefore, must be stationary in a plane parallelto the A datum. That is to say, third and fourth alignment structures 68and 70 can move up and down within the confines of holes 40 and 42, butthey can't move front to back or side to side. Third and fourthalignment structures 68 and 70 are usually vertically projecting pins asdepicted in the Figures, but any other structure suitably configured toproject into holes 40 and 42 can be used.

The alignment structures 64, 66, 68 and 70 will now be referred to forconvenience simply as alignment pins. In the embodiment shown in FIGS.4-12, chamfered alignment pins 68 and 70 are used instead of thechamfered holes of the cartridge illustrated in FIG. 3. Either or bothof alignment pins 68, 70 and holes 40, 42 may be chamfered as necessaryor desirable to accommodate misalignment between the pins and the holes.

Recess 38 in front planar surface 30 a of cartridge housing 12 is usedto help align cartridge 10 to the B and C datums. The front to backdepth of recess 38 is used to help align cartridge 10 to the B datum inconjunction with first and second alignment pins 64 and 66 in tape drive50. The purpose of this comparatively coarse prealignment is to minimizethe misalignment tolerance between holes 40, 42 and alignment pins 68and 70. Minimizing this misalignment tolerance reduces the verticaltravel required to precisely align cartridge 10 on pins 68 and 70.

Referring now to the motion depicted by comparing FIGS. 4/5 and 9/10, asholder 60 is retracted into tape drive 50 to move cartridge 10 to theoperating position, first and second alignment pins 64 and 66 abut thefront side 30 of cartridge 10 at recess 38 and planar surface 30 a,respectively. Holder 60 is retracted horizontally until first alignmentstructure 64 bottoms out in recess 38 and second alignment structure 66abuts planar surface 30 a, as shown in FIGS. 5 and 10. First alignmentstructure 64 is positioned behind second alignment structure 66 adistance equal to the depth of recess 38 so that first alignmentstructure 64 bottoms out in recess 38 at the same time second alignmentstructure 66 abuts planar surface 30 a. At this point, front planarsurface 30 a is generally aligned with the B datum. In some cases it maybe desirable, as shown in FIG. 5, to intentionally misalign third andfourth alignment pins 68 and 70 slightly behind holes 40 and 42. Thismisalignment is used to draw cartridge 10 back slightly away from pins64 and 66 as cartridge 10 is moved down to the fully installed operatingposition.

Next, holder 60 is moved down to position cartridge 10 on alignment pins68 and 70. This movement is seen by comparing FIGS. 5/6, 7/8 and10/11/12. The slight misalignment noted above causes the chamfered pins68 and 70 to draw cartridge 10 back slightly as the pins slide intoholes 40 and 42. The final position of cartridge 10 is shown in FIGS. 6,8 and 12.

The bevel of recess 38 positions holes 40 and 42 over pins 68 and 70along the B datum (from side to side). If first alignment structure 64is misaligned to the center of recess 38, cartridge 10 will move fromside to side as the bevel of recess 38 is driven against alignment pin64 until alignment structure 64 bottoms out at the center of recess 38.It is desirable, therefore, to bevel recess 38 on both sides to form theV shaped slot shown in the Figures to accommodate misalignment of firstalignment structure 64 to either side of the center of recess 38. Also,if first alignment structure 64 is formed as a vertically projectingpin, then V shaped recess 38 must be open to the bottom 20 of housing 12to allow cartridge 10 to slide freely up against first alignmentstructure/pin 64 at recess 38.

First and second alignment pins 64 and 66 are positioned on oppositesides of the front 30 of housing 12, preferably as far apart as possibleto optimize B and C datum pre-alignment. Correspondingly, it isdesirable to locate recess 38 as far as possible to the side of frontside 30 of housing 12. Front planar surface 30 a need not be continuousacross the front of cartridge housing 12. Indeed, front planar surface30 a need not exist at all. What is important is that when firstalignment structure 64 bottoms out in recess 38 and second alignmentstructure 66 abuts some structural feature on the front 30 of cartridgehousing 12, then cartridge 10 is substantially aligned with the B and Cdatums and holes 40 and 42 are positioned over pins 68 and 70.“Substantially aligned” means good enough to align pins 68 and 70 withinthe chamfer reach of holes 40 and 42 (or the chamfer reach of pins 68and 70 if the pins are chamfered).

While it is expected that front 30 of cartridge housing 12 will usuallyinclude a tangible planar surface, such a tangible surface is notnecessary to the invention. Hence, the term planar surface should beconstrued broadly to include both a tangible planar surface and anintangible plane that extends across an irregular non-planar front 30,side 26, top 18 or bottom 20 of cartridge housing 12. One of the holes40 or 42 may be a slot as long as the long axis of the slot iscoincident to the line between the two holes.

The invention as shown and described in these illustrative embodimentsincludes the steps and structures necessary for understanding andexplaining the structure and use of the invention. Other typical stepsand structures that are normally related to the use of a tape cartridgeand a tape drive that are well known to one skilled in the art but thatare not essential to understanding the invention are not described indetail. Although the positioning system of the present invention hasbeen described with reference to a single reel tape cartridge such asthe one illustrated in FIG. 1, the system may be used in various othertypes of removable data storage cartridges and devices. Also, the tapecartridge has been described with reference to top, bottom and sides.These generally planar surface descriptions, however, are not intendedto limit the invention to horizontally oriented tape drives in whichtape cartridges are inserted with the gear opening down. The inventionis equally applicable to vertically oriented tape drives or tape drivesthat might be skewed to the horizontal or vertical planes. Hence,relative terms like top and bottom or up and down should be construedbroadly to include comparable features on any data storage cartridge ordevice without regard to its operationally orientation. It will,therefore, be understood that modifications to and variations on theembodiments shown and described are possible without departing from thescope of the invention which is defined in the following claims.

What is claimed is:
 1. A system for positioning a data storage cartridgein a read/write mechanism, the cartridge characterized by a first planarsurface that fronts the read/write mechanism and a second planar surfaceperpendicular to and extending away from the first planar surface, thecartridge movable in a first direction from a loading position to apre-aligned position in which the cartridge is partially installed inthe read/write mechanism and then in a second direction transverse tothe first direction from the pre-aligned position to an alignedoperating position in which the cartridge is fully installed in theread/write mechanism, the system comprising: a beveled recess in thefirst planar surface; a pair of holes in the second planar surface; andfirst, second, third and fourth alignment structures affixed to theread/write mechanism, the third and fourth alignment structures orientedperpendicular to and projecting out toward the second planar surface;the first alignment structure disposed such that as the cartridge ismoved toward the pre-aligned position the first alignment structureabuts the beveled recess; and the first, second, third and fourthalignment structures disposed such that when the cartridge reaches thepre-aligned position the first alignment structure bottoms out in thebeveled recess, the second alignment structure abuts the first planarsurface at a location away from the beveled recess, the third alignmentstructure is substantially aligned with one of the holes in the secondplanar surface and the fourth alignment structure is substantiallyaligned with the other of the holes in the second planar surface.
 2. Asystem according to claim 1, wherein the holes are spaced apart from oneanother along a line parallel to the first planar surface.
 3. A systemaccording to claim 1, wherein the holes are spaced apart from oneanother along a line perpendicular to the first planar surface.
 4. Asystem according to claim 1, wherein the holes comprise chamfered holes.5. A system according to claim 1, wherein the third and fourth alignmentstructures comprise chamfered pins.
 6. A system according to claim 1,wherein the first planar surface defines a plane along the front of thecartridge and the second planar surface defines a plane along the bottomof the cartridge.
 7. A system according to claim 1, wherein the thirdand fourth alignment structures project into the holes when thecartridge reaches the operating position.
 8. A system according to claim1, wherein the beveled recess comprises a V shaped recess.